Penicillium charlesii synthesizes substantial quantities of a glycopeptide which contains approximately 120 mannopyranosyl and galactofuranosyl residues in a polysaccharide region and an oligosaccharide region each attached to a common peptide. In addition the polysaccharide contains ethanolamine and phosphorus. This research has two broad objectives. The first is to establish if the oligosaccharide and polysaccharide regions are synthesized independently and if the polyprenol phosphates function as a cofactor in the incorporation of mannosyl residues into either region. The second objective is to determine the stage of glycopeptide assembly at which the ethanolamine is incorporated. The first objective will be accomplished by measuring the specific activity of the mannose containing oligosaccharides and mannose in the polysaccharide as a function of time after exposing the culture to (C14)-D- glucose for relatively short intervals, and by in vitro experiments determine if polyprenol phosphates influence the extent and rate of incorporation of mannose from GDP-mannose into either the polysaccharide or the oligosaccharide region. The distribution of C14- mannose from GDP-(C14)-D-mannose will be examined after partially degrading the polysaccharide by acetolysis and by examining the products following methylation. The second objective will be accomplished by determining the time course of ethanolamine incorporation in vivo into the glycopeptide compared to mannose incorporation and by determining if CDP-ethanolamine will serve as a donor of ethanolamine (or phosphoryl ethanolamine) in vitro, using the glycopeptide or modified glycopeptide as an acceptor. Experiments with fortifiers such as polyprenol phosphates, GDP-mannose and metal ions added will be conducted to determine if some combination of these will promote ethanolamine incorporation into the glycopeptide.